In recent years, internal combustion engines used in motor vehicles have been equipped with emission control systems to prevent non-combustible matter from entering the exhaust manifold of the engine and being discharged to the atmosphere. Such engines are commonly equipped with a PCV valve which draws fumes from the crankcase and recirculates it through the engine. The PCV value has a number of disadvantages. Its opening is not adjustable to compensate for the need for an increasing flow of fumes from the crankcase as the vehicle becomes older, and therefore it often does not provide proper ventilation. The PCV valve also does not separate engine oil from the crankcase fumes being recirculated through the engine. Oil in the fumes from the crankcase mixing with the engine gasoline supply at the base of the carburetor can have the effect of reducing gasoline octane. The result is reduced horsepower and lower gasoline mileage. Oil carried with recirculating crankcase fumes causes increased oil consumption and smoke emission from the tail pipe. The PCV value also needs cleaning and replacing to maintain a reasonable level of reliability.
My U.S. Pat. No. 3,494,339 decribes a self-cleaning smog control filter in an induction system for recycling crankcase fumes through an internal combustion engine to reduce air pollution from the exhaust system of the engine. The self-cleaning smog control filter includes a wire coil spring in a filter connected to the engine crankcase in combination with the air filter connected to the carburetor induction system. All gaseous fuels are recycled from the crankcase through the engine to prevent non-combustible matter from entering the exhaust manifold of the engine. The self-cleaning smog control filter and induction system as a number of advantages over the PCV crankcase value. The filter does not need cleaning or replacing; and it separates oil from the crankcase fumes and returns the oil to the crankcase, permitting the gas and other combustible elements to recirculate through the combustion system. It does not have the effect of lowering octane or engine performance level. The filter also provides proper crankcase ventilation through different sized orifices which allow all crankcase fumes (blow-by gas) to be drawn into the intake manifold independent of engine life. The filter provides a substantial reduction in hydrocarbon and carbon monoxide exhaust emissions.
The present invention is an improvement to the self-cleaning smog control filter described in U.S. Pat. No. 3,494,339. The self-cleaning smog control filter described in that patent includes a rotating lever arm rigidly affixed to the coil spring filter. An inertial weight at the end of the lever arm senses acceleration and deceleration of the vehicle and rotates the lever arm which, in turn, rotates the coil spring filter during use. Rotation of the coil spring filter provides a means for self-cleaning the filter as well as responding to the motion of the vehicle to regulate the flow of vapors through the filter. The lever arm rotates between external stops on the filter housing to limit the winding and unwinding motion of the coil spring filter.
There is a need to ensure that a preset amount of filtration can be produced by such a coil spring filter, and that this amount of filtration can be reliably maintained during the life of the vehicle. If the coil spring filter becomes too slack, for example, then proper filtration is prevented and the vehicle's performance level is diminished. There is also a need to ensure that the restrictions on maximum winding and unwinding of the coil spring filter during use are accurately controlled and maintained throughout the life of the vehicle.